I'm not sure, but I think it is nothing but math:

126/2*3=189 (or the other way around: 190/3*2=126 rounded)

4/4 is 4 beats per measure, id est that's two thirds of the 6 beats per measure of a 6/8 time signature.

Internal mathematical operations seem to convert beats per minute to measures per minute even if beats per minute are shown.

Guido "I'm wild guessing" Haas


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